A Florida Atlantic University public opinion poll released Saturday showed Donald Trump with 44 percent of the vote and Marco Rubio and Ted Cruz with 21 percent each. With the primary just days away, 5 percent of Florida Republicans still hadn't made up their minds.

If the numbers hold through Tuesday's primary, the billionaire businessman and part-time Palm Beach resident would win all of Florida's 99 nominating delegates in the winner-take-all primary.

If Rubio, Florida's junior U.S. senator, fares as poorly in actual votes in his home state as the poll indicates, it would be a devastating blow to his presidential hopes. If Cruz, a senator from Texas, finishes even with Rubio, that could boost his argument that he's the best alternative to Trump.

The FAU poll's 23-point advantage for Trump is larger than the RealClearPolitics average of Florida polls released in the last week. The polling average has Trump 14.7 points ahead of Rubio.

FAU found Clinton with support of 59 percent of Democrats with 31 percent for Sanders

She has a 28-point advantage in the new FAU poll, down from her 36-point lead in January. The latest RealClearPolitics average has her ahead by 34.2 points.

With four other big states holding primaries Tuesday, Sanders has effectively ceded Florida to Clinton. His only campaign appearances in Florida took place when he was going to be in the state anyway – the day before and the day after Wednesday's Democratic candidates' debate in Kendall.

Clinton, by contrast, has appeared more frequently in Florida, has dispatched surrogates to the state, and has targeted television and radio ads to key Democratic Party constituencies: seniors, blacks and Hispanics. On Saturday, her campaign announced an effort aimed at the Caribbean-American community.

Clinton leads 75 percent to 6 percent among Hispanics and 75 percent to 18 percent among black voters. Sanders leads 63 percent to 24 percent among voters 34 and under. She leads among all other age groups.

With his political future riding on Tuesday's results, Rubio had a punishing schedule Saturday, with events in Largo, Hudson, Tampa, Lakeland and Pensacola. Rubio surrogates were also out in force — wife Jeanette in Jacksonville and Orlando; U.S. Sen. Tim Scott of South Carolina in Boca Raton and Fort Lauderdale; U.S. Rep. Mia Love of Utah in Miami, and South Carolina Gov. Nikki Haley in Pinellas and Sumter counties.

Trump held rallies in Ohio, Cruz held rallies in Missouri, and Gov. John Kasich of Ohio was in his home state.

Kasich had 9 percent of the vote in FAU's poll of Florida Republicans.

"The truth is that very little has changed," said Kevin Wagner, an FAU political scientist and research fellow at the university's Business and Economics Polling Initiative, which conducted the survey. "The gap has been narrowed a little bit. But Donald Trump continues to dominate the field, and he has pretty much for months."

Trump's support is statistically unchanged from January, when FAU reported he had support of 48 percent of Florida Republicans. Rubio has surged since January, when he was at 11 percent, evidently benefiting as other candidates, including former Gov. Jeb Bush, dropped out of the presidential race. Cruz has also risen from 16 percent in January.

Trump has a narrow lead among Hispanic Republicans. He has 37 percent, Rubio 34.5 percent, Cruz 20.5 percent and Kasich 8 percent.

Wagner said Rubio could still pull out a victory.

"A poll is just a snapshot. Things change after we snap that picture. It's certainly not impossible for a candidate to make up a lot of ground. We've seen candidates surge in the last few days [of a campaign]. Those things are possible, but the margins in this case make it a tough task," he said.

The survey of 414 Democrats and 852 Republicans considered likely voters was conducted through automated telephone calls Tuesday through Friday. It has a margin of error of plus or minus 5 percent for the Democratic survey and 3 percent for the Republican survey.

The survey found that the sometimes-brutal campaign among the Republicans has taken a toll. All the candidates' favorability ratings are down since the last FAU poll in January, Wagner said.

Kasich, who has been emphasizing a positive message and not attacking the others, has the highest favorability rating among Republican voters: 60 percent, with just 28 percent unfavorable.

Trump is rated positively by 56 percent — down from 70 percent favorability in January — and negatively by 41 percent. Rubio is viewed favorably by 48 percent, negatively by 45 percent. And Cruz is viewed favorably by 44 percent and negatively by 49 percent.

"The sharp decline in their approval ratings from when we polled in January until now should be worrisome to the Republicans about how any of these candidates will do in the general election in Florida," Wagner said.